Treatment of wood and product thereof



' July 24, 1928.

B. FORD TREATMENT OF WO0D AND PRODUCT THEREOF Filed Sept. 22. 1922 .BfaCe Fora 2r W l2,

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Patented July 24, 1928.

UNITED STATES BRUCE FORD, OF PHILADELPHIA, PENNSYLVANIA.

TREATMENT OF WOOD AND PRODUCT THEREOF.

Application filed September 22, 1922. Serial 170.589,.930.

The principal object of the present invention is to provide dry Wood which will not swell when wetted and which, therefore, is

useful for many purposes and in many forms, for example, in the form of Veneer it is useful for separators in storage or secondary batteries in which use its porosity is an added valuable attribute or quality,

Treated wood of the invention in respect to an equalweight of ordinarily dried or seasoned wood of the same kind or variety possesses the volume of wet 'wood of the same kind, but is characterized by the absence of' swelling when wetted;v in other words, the wood of the invention is more porous than wood of the same kind shrunk in consequence of drying. Another way to describe the treated wood 'of the invention is to say that its specific gravity is lower than that of wood of the same kind or species that has been permitted to follow its natural tendency and shrink in drying or being dried by known methods. The important feature of dried wood of the invention is that it will not swell when wetted and herein it differs from any dry wood known to me prior to my present invention.

The method of the invention, generally stated, consists in wetting the wood as by soaking it and heating the wetted wood while confined against swelling or disruption of its structure in order to dry it by the evaporation or evolution'of moisture in its pores faster than vapor escapes from its pores, which constitutes what I may call restrained expansive drying in contra-distinction to known shrinkage drying.

The method can be practiced in at least either of the'two following ways: The natural wood, whether green, seasoned'or dried by known methods, for example in board or veneer form, is soaked or boiled in an aqueous liquid in order to wet it and the wet wood can be held .firmly between two hot I have produced satisfactory results by clamping a sheet of previously soaked red wood veneer about 5 by 6 inches and of an inch thick between two iron plates at a temperature of 450 to 470 F., more or less, and of about the same size as the sheet of wood and of an inch thick for three minutes. Instead of using clamping, or mechanical restraint of expansion, with heat alone, I may employ both heat and pressure. To do this the wood is mechanically held against expansion as between two properly secured plates arranged in a closed chamber in which steam under pressure can be confined and then released. For a veneer of an inch thick, steam at 130 pounds for 1 4, minutes is an example.

In eachcase moisture is vaporized in the pores faster than it escapes therefrom generating an expansion or disruption tendency in the structure of wood which, however, is mechanically opposed or restrained. In the first case the vaporization is relatively slow, although its escape is readily noticeable. In the second case the vaporization is comparatively sudden and occurs when the pressure is released.

Referring to the accompanying drawings: Figure 1 is an elevational view illustrative of the foregoing description.

Fig.2 is a View in end elevation illustrating a modification.

Fig. 3 is a plan view of a part of the device shown in Fig. 2, and

Fig. 4 is a view, principally in section, illustrating a modification.

Referring to Figure 1, 1 and 2 are plates as of iron that can be heated to, for example, from 450 'F. to 470 F., more or less, as by means of the Bunsen burner 3. tare clamping means for restraining or opposing expansion or undue expansion of the wood a. i

The construction shown in Fig. 2 is substantially the same with the exception that the plates 1 and 2 are hinged together as at 4 and are hooked together as at 5. Furthermore around the portion of the plates that bears upon the wood a there is providcd'a channel or groove 6 having a valved outlet connection 7. In this apparatus the escape of the vapor from the wood is positively and controllably restrained. As shown in Fig.

in Fig. 1 are arranged in a closed chamber 8 fitted with a valved inlet 9 for the introduction of high pressure steam and with a valved outlet'10.

Obviously modifications may be made in details and matters of form, hence the invention is not limited to such things or otherwise than as the prior art and the appended claims may require.

I claim:

1. Dry Wood of its original size as treated by the process of claim 6 and characterized by the absence of swelling when wetted and by the presence of porosity.

2. The process of treating wood which consists in vaporizing moisture in the pores faster than it can escape therefrom by the application of heat to the wood, opposing the disruptive tendency of the vapor accumulating in the pores by mechanically l restraining the wood against expansion, and

while the Wood is mechanically restrained permitting the evacuation of the vapor from the pores.

3. The process of treating wood which consists in vaporizing moisture in the pores faster than it can escape therefrom by the application of heat and pressure to the wood,- opposing the disruptive tendency of the vapor accumulating in the pores by mechanically restraining the wood against expansion, and while the wood is mechanically restrained evacuating the accumulated vaporfrom the pores by suddenly releasing the pressure.

4. In the process of drying wood the improved step which consists in confining the ezzees wood against expansion and forming vapor in the pores faster than it escapes to generate internal pressure sufiicient to oppose shrinkage, substantially as described.

- 5. The process of treating wood which consists 1n drying it so rapidly that it' would expand or disrupt if unconfined and confining it against such expansion or disruption, substantially as described.

6. The process of treating wood which consists in wetting the Wood by introducing moisture into its pores, vaporizing the molsture in the pores faster than it can escape therefrom by the application of heat to the wood, opposing the disruptive tendency of the vapor accumulating in the pores by mechanically restraining the wood against expension and while the wood is mechanically restrained permitting the evacuation of the vapor from the pores.

7. Dry wood of its original size as treated by the process of claim 6 and characterized by the absence of swelling when wetted and by the presence of porosity.

8. Dry wood of its original size as treated by the process of claim 6 and characterized by the absence of swelling when wetted and being the product of a process in Which shrinkage in drying is opposed and prevented.

BRUCE FORD. 

